The paper considers collisions of spin-polarized atoms with electron spin S = 1, in a situation where at least one of them is in an excited state. In this case, both the spin polarization exchange between the colliding atoms and the ionization of atoms due to the internal excitation energy occur during the collision. In the paper, expressions are obtained for the complex cross sections of spin exchange accompanied by ionization, including expressions for the cross sections of the magnetic resonance frequency shift, which is the imaginary part of the complex cross section of spin exchange. Using two metastable helium atoms in the 2³S₁-state as an example, the energy and temperature dependences of the frequency shift cross sections were calculated. The frequency shift cross section was found to influence, in the case of the ⁴He isotope, only the alignment, and this influence occurs only during the interference of elastic scattering amplitudes on the singlet and quintet terms of the He₂ quasimolecule. It was shown that the ionization process occurring simultaneously with the spin exchange significantly affects the magnitudes of the magnetic resonance frequency shifts in a mixture of helium isotopes. In addition, it turned out that the magnitudes of the frequency shifts caused by the spin exchange are commensurate with the magnetic resonance frequency shifts caused by the metastability exchange between helium atoms in the metastable and ground states. Keywords: atomic collisions, polarized atoms, cross sections, magnetic resonance frequency shifts.

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